It is well known that the ability of the human eye to simultaneously perceive details in both brightly and dimly lit areas is unmatched by traditional image capture devices. Consequently, a photographer may perceive a scene via their naked eye as having detail in both brightly lit and dimly lit areas, but, when photographed, the resulting photograph of that same scene can comprise brightly lit areas that are “washed out” and devoid of detail, and can comprise dark areas that are, analogously, too dark and, likewise, devoid of detail. Professional photographers are well aware of this pitfall and guard against it through a variety of means that can be implemented prior to capturing the image. Amateur photographers, on the other hand, are traditionally not aware of such limitations in their image capture equipment and, as a result, obtain images that are devoid of detail.
With the advent of digital image capture and digital image processing techniques, various mechanisms can be applied after an image is captured to ameliorate the loss of detail in brightly or dimly lit areas of the image. Typically such mechanisms are referred to as “highlight and shadow” processing. Manual highlight and shadow processing functionality can be found in most digital image editing software application programs. However, because the highlight and shadow processing offered by such programs is manually adjusted by the user, the ability to improve a given image is directly dependent upon the ability of that user to utilize such functionality in a skilled and informed manner. Unfortunately, those users that are not sufficiently savvy to avoid taking such photographs in the first place are, similarly, unlikely to be skilled at utilizing the highlight and shadow processing to fix such photographs after the fact.
In recognition of this dichotomy, some digital image editing software application programs offer automated highlight and shadow processing, often nominated “auto exposure”. Such automated processing, however, applies the same modifications to the entire digital image. There is no attempt made, by such automated processing, to distinguish which areas of the digital image represent highlights, which areas represent shadows, and treat those areas differently, or apply different modifications to those distinct areas. Instead, such automated highlight and shadow processing determines the digital modifications to be applied based on the whole image, in aggregate, and applies those modifications to the whole image.